High pass and notch filter questions.

[estefan2020]

Hi, I I live in a town that has 3 bcb transmitters, that bleeds an could use some help.

I would like to create a high pass filter (1470K AM) is bleeding into the short wave 1.8Mhz on up. Not interested in the AM BCB

I would also like to create 2 notch filters (92.5M FM) (100.1M FM) 92.5M also bleeds forwards.

Is there a software program that can use create high pass filter for the 1470k am signal that still sends 1.8Mhz , and 2 notch filters for the 2 fm frequencies.

I would like to update the inductor values and float capacitor values, so I can use parts that can be ordered from e-bay, or other suppliers if possible.


Any help would be appreciated.
Dan

 

[BradtheRad]

This looks like a job for a wavetrap or 3. There may be commercial units that do what you want, but you can probably do a better job yourself.

Link to a thread at this board, discussing wavetrap for 10kHz:

https://www.edaboard.com/threads/71987/

Informative links:

Dave's Homemade Wave-Trap. **** out those local stations that make your DXing ****!

Wave Trap

TheRadioBoard :: View topic - wave trap schmatic

A poster at the last link (Dan M) recommends a utility called 'Professor Coyle' for calculating what values to use.

He also states:
"I've found that how much the target frequency is reduced depends on the overall coil construction and the frequency - but - the biggest effect is the ratio of the # of turns in the primary coil, to the # of turns in the secondary coil."

 

[RF_Jim]

Hi, I I live in a town that has 3 bcb transmitters, that bleeds an could use some help.

I would like to create a high pass filter (1470K AM) is bleeding into the short wave 1.8Mhz on up. Not interested in the AM BCB

I would also like to create 2 notch filters (92.5M FM) (100.1M FM) 92.5M also bleeds forwards.

Is there a software program that can use create high pass filter for the 1470k am signal that still sends 1.8Mhz , and 2 notch filters for the 2 fm frequencies.

I would like to update the inductor values and float capacitor values, so I can use parts that can be ordered from e-bay, or other suppliers if possible.


Any help would be appreciated.
Dan

Dan,

Did you need 'brickwall' (absolutely guaranteed to block the BCB) performance?

Like 40 dB guaranteed performance?

This design includes a schematic on the second page and measured performance on the 5th page even a SPICE simulation to boot:

AM Broadcast Band (BCB) Brickwall Filter, 160M - 10M pass, Design and Performance


It uses four T106-2 cores ... although something smaller can be used if you arrive at the same inductance values as shown on the schematic ...

Jim